Viscosity stable oxidized polymer solutions



S at Patent VISCOSITY STABLE OXIDIZED POLYMER e r SOLUTIONS Donald F. Koenecke, Westfield, -NJ., assig'nor to Esso Research and Engineering Company, a corporation of Delaware I t 1 No Drawing. Application December 7, 1956 e ,Serial'No.j626,839

12 Claims. (Cl. 106-287) 'Il1'isinvention relates toa method for the preparation of synthetic drying oils of improved properties and more particularlyrelates to a method for preparing a viscositystable product. V

Synthetic drying oils can be prepared by various methods from butadiene alone or from mixtures containing butadiene together with materials copolymerizable therewith. -Sodium polymerization, emulsion polymerization aswellasbulk or mass polymerization in the presence of a diluent and a peroxide type catalyst have been used for xthispurpose with varying degrees of success. However, among the diificulties encountered with various synthetic drying oils were poor drying rate, poor flexibility 'and poor adhesion of air-dried coatings, poor wetting properties and consequent difficulty of grinding inpigments, poor gloss and streakiness of brushed enamel films preparedfltherefrom. While some of these disadvantages h'avebeen overcome in the past, the corrective measures employed usually have resulted in aggravation of other undesirable characteristics. In general the sodiurn catalyzed polymers have been found to be most economical to produce and to have a good drying rate but at the same-time this type of drying oil was found to have particularly poor pigment wetting power and enamelsprepared therefrom gave dull "and very-Streaky films-by brushing. v. r.

Most of-these disadvantages can be overcome by oxidizing the-oily copolymer by blowing with air or oxygen in. the presence of a solvent, preferably aromatic, and preferably a catalyst such as a small amount of a metal naphthenate or other drier. These oxidized oils contain up to about 20% oxygen and have much improved pigment-wetting characteristics. However, the oxidized product generally has very poor viscosity'stability, often becoming too viscous to handle even after comparatively short storage periods. For practical commercial uses a viscosity increase of-more than 1 poise in 6 months in undesirable. r

It has now been discovered that the ditficulties inherent in the oxidized product can be circumvented by at least' partially replacing the hydrocarbon solvent with a liquid saturated alcohol. The normal aliphatic alcohols containing 1 to 9 carbon atoms are particularly suitable. In addition, isopropyl alcohol, diacetone alcohol, acetyl carbinol, trimethyl carbinol, methyl, ethyl carbinol, isobutyl carbinol, secondary butyl carbinol, dimethyl ethyl carbinol and benzyl alcohol are also suit able. Those containing up to carbon atoms are preferred. The amount of alcohol added may be from 1% up to the tolerance limits of the solution, preferably 525%. Since the lower alcohols are not solvents for theoxidized polymer, excessive amounts will precipitate the polymer. When small amounts of these alcohols are added, an immediate viscosity decrease is observed over. and above that obtained with the same amount of hydrocarbon solvent.

The synthetic oils to which the present invention is applicable are oily polymers of butadiene, isoprene, dimethyl butadiene, piperylene, methyl pentadiene or other conjugateddiolefins having four to six carbon atoms per molecule. Instead of polymerizing any of the afores aid diolefins alone, they may be copolymerized in ad wise specified.

Patented oct, 13, 19 59 mixtures with each other or in admixtures with minor amounts of ethylenically unsaturated monomers copolymerizable therewith, e.g., with 5 to 30% of styrene, styrenes having alkyl groups substituted on the ring such as para methyl styrene, dimethyl styrene or diethyl styrene, acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, vinyl isobutyl ether, methyl vinyl ketone, and isopropenyl methyl ketone. Such synthetic oils may be advantageously prepared by mass polymerization either in the presence of a hydrocarbon soluble peroxide catalyst such as benzoyl peroxide or cumene hydroperoxide, or in the presence of metallic sodium when the monomers consist of a diolefin or of a mixture of a diolefin with a styrene compound. Under proper conditions the emulsion polymerization technique may also be adapted to the preparation of drying oils to which the present invention is applicable. Suitable polymerization methods are illustrated below. Through out the present description it will be understood that all proportions are expressed on a weight basis unless other- SYNTHESIS METHOD A For example, 100 parts of butadiene-1,3, parts of straight run mineral spirits boiling between 150 and 200 C. (Varsol), 3 parts of t-butyl hydroperoxide (60% pure) and 0.75 part of diisopropyl xanthogen disulfide are heated in a closed reactor at about 90 C. for 40 hours, whereupon the residual pressure is released and lmreacted butadiene is allowed to volatilize from the polymerized mixture at 70 C. The resulting product, which is a clear, water-white solution, consists typically of about 60 parts of oily polymer of butadiene, about 4 parts of butadiene dimer, plus solvent and some t-butyl alcohol. This solution of polymer is then preferably fractionated to remove the dimer and usually adjusted to 50% non-volatile matter content. The non-volatile constituent, which is the oily polymer of butadiene, has a molecular weight between 1,000 and 10,000, preferably between 2,000 and 5,000. It will be understood, of course, that the foregoing procedure is only illustrative and that it can be modified in many .ways, particularly as described in U.S. patent application, Serial No. 782,850 of Arunda le et al., filed on October 29, 1947, now Patent No. 2,586,594, which describes alternative monomers, catalysts, reaction diluents, polymerization modifiers, suitable ranges of proportions of the various An alternative polymerization method using sodium as catalyst is illustrated as follows: 80 parts of butadiene- 1,3, 20 parts of styrene, 200 parts of straight run mineral spirits boiling between 150 and 200 C., 40 parts of dioxane, 0.2 part of isopropanol and 1.5 parts of finely dispersed sodium are heated at about 50 C. in a closed reactor provided with an agitator. Complete conversion is obtained in about 4.5 hours whereupon the catalyst is destroyed by adding an excess of isopropanol to the polymerized charge. The crude product is cooled, neutralized with carbon dioxide or glacial acetic acid or other anhydrous organic acid and filtered. Instead of neutralizing the alcohol treated product, the acid may also be added directly to the crude product containing residual metallic sodium and the latter destroyed by the acid. The colorless filtrate is then fractionally distilled to remove the alcohol and modifiers such as dioxane.

" 2 10,000, preferably between about 2,000 to 5,000.

Again it will be understood that the described sodium polymerization method may be varied considerably as by omitting the styrene co-reactant; or by adding the styrene only after the polymerization of butadiene monomer had'begun; or dioxane may be replaced by 10 to 35 parts of another ether modifier having 3 to 8 carbon atoms such as methyl ethyl ether, dibutyl ether or phenetole; or the modifier may be omitted altogether, especially when it is not essential to obtain a perfectly colorless product. Similarly, isopropanol is not necessary, though aliphatic alcohols of less than 6 carbon atoms generally have the beneficial effect of promoting the reaction when present in amounts ranging from about 2 to 50% based on the weight of sodium catalyst. Furthermore, the mineral spirits may be replaced by other inert hydrocarbon diluents boiling between about 150 C. and 250 C., preferably between 60 and 200 C., e.g., butane, benzene, xylene, naphtha, cyclohexane and the like. The diluents are usually used in amounts ranging from 50 to 500 parts per 100 parts of monomer. The reaction temperature may vary between about 40 C. and 100 (3., preferably around 65 to 85 C. As a catalyst, 0.1 to 10 parts of dispersed metallic sodium is used per 100 parts of monomers, sodium particle sizes below 100 microns being particularly effective.

The blowing of the polymeric drying oils is best carried out in a hydrocarbon solvent of moderate to good solvency, e.g., solvents or solvent mixtures having a kauri butanol value of at least 40. At least a substantial portion of aromatic solvent is generally needed to secure such a KB value, and such aromatic content is highly beneficial in promoting oxygen uptake during the blowing treatment. It also aids materially in permitting high oxygen contents to be secured in the treatment Without encountering the instability which induces gelation of the mass being treated. Other strong solvents, such as oxygenated solvents, have similar benefits. While mixtures of high and low kauri butanol value solvents are generally useful, the oil can be dissolved in strong solvent(s) from the start, thereby eliminating low solvency solvents. The choice of solvents will, of course, depend on the oxygen content which is desired in the finished oil as well as on the formulations of the coating compositions which are to be made from the blown oil, and in the interest of economy it is generally desirable to use the cheapest solvent(s) which possess the needed attributes of kauri butanol value and compatability with the various ingredients of the finished coating vehicle which is to be formulated.

Examples of suitable solvents include aromatic or mixtures of aromatic and aliphatic hydrocarbons boiling up to about 250 C. The aromatic solvent may be benzene, toluene, hemi-mellitene, pseudocumene, mesitylene, propyl benzene, cymene, ethyl toluene, methyl ethyl benzene, xylenes, Solvesso 100 (a mixture of aromatic hydrocarbons boiling from about 150 to 175 C.), Solvesso 150 (a mixture of aromatic hydrocarbons boiling from about 190 to 210 C.), or mixtures thereof. Other suitable solvents include the Varsols which are straight run mineral spirits boiling in the range of 140 to 205 C., having API gravities of 40 to 55 and varying in aromatic content from to 35 wt. percent.

Catalysts suitable for the oxidation reaction of this invention include organic salts of metals such as the naphthenates, octoates, and other hydrocarbon soluble metal salts of cobalt, lead, iron and manganese. These catalysts are used in amounts ranging from 0.001% to 1.0%. Peroxides such as benzoyl peroxide and the like may be added to reduce the induction period.

It is understood that conditions of temperature and time of reaction, ratio of reactants, degree of dilution, presence or lack of solvents and the like will depend upon factors including the degree of oxidation desired and the nature of the starting polymer; therefor, it is not 4 intended that the invention be limited by the specific conditions and examples herein set forth as it is intended to illustrate and not limit the invention.

The nature of the oxidized diolefin polymer depends largely upon the extent'of oxidation which in turn depends on various factors including time of oxidation, temperature, presence or absence of catalysts, type of solvent, etc. In general, greater extent of oxidation results in a lower solubility of the oxidized polymer in paraflin hydrocarbon solvents. The oxidation can be carried out such that the product is soluble in paraflinic hydrocarbons indicating that the oxidation has proceeded to a relatively slight extent. The oxidation can also be carried out so that the product is insoluble in paraflinic solvents but is completely soluble only in aromatic solvents indicatingthat the oxidation has proceeded to a high degree. The percent of oxygen in the product will vary according to the conditions from a trace. to 20% or more.

According to this invention, a liquid polymer oil resulting from an alkali-metal catalyzed polymerization and subsequent oxidation in the manner described is made stable to viscosity changes by the addition of a small amount of one of the alcohols described above. As previously mentioned, this results immediately in a substantial viscosity decrease but also and more importantly the viscosity changes very little, if at all, after an extended period of storage.

The following specific examples are presented to illustrate typical applications and eifects of the present invention. All quantities are expressed in this specification and claims on a weight basis unless stated otherwise.

Example I.A butadiene-styrene drying oil was prepared from the following charge:

1 Straight run mineral spirits; API gravity, 49.0; flash, F.; boiling range, to 200 0.; solvent power, 3337 kauri-butanol value (reference scale: benzene-100 KB. value, n-heptane 25.4 KB. value);

2 Dispersed to a particle size of 10 to 50 microns by means of an Eppenbach homo-mixer.

The polymerization of this charge was carried out at 50 C. in a 2liter autoclave provided with a mechanical agitator. Complete conversion was obtained in 4.5 hours. The catalyst was destroyed and removed from the resulting crude product and essentially all of the sol- 'vent removed by stripping to give a product of essentially 100% N.V.M. (percent polymer in total or'nonvolatile matter). The resulting product had a viscosity of 1.5 poise at 50% N.V.M. in Varsol solution and the nonvolatile portion thereof had an average molecular weight of about 3,000.

The polymer oil thus obtained was dissolved in Solvesso 100 and blown with oxygen to various oxygen contents. Samples of these blown oils were reduced with small amounts of n-butanol and compared in viscosity with the same sample reduced with comparable amounts of Solvesso 100. The results are shown in the following table:

Sample Percent NVM Reduced NVM Poise Gardner, No. 0. with Viscosity Viscosity 12. 8 50. 1 Nothing- 17. 0 Y 12. 8 50. 1 n-ButanoL 47. 6 3. 4 N 12. 8 50.1 Solvesso 10 47. 6 12. 9 X 11.9 50. 8 Nothing- 50. 8 5.0 S 11. 9 50. 8 n-ButanoL 48. 2 2. 25 I 11.9 50.8 Solvesso 100- 48. 2 4. 0 P 7 9. 7 41. 2 Nothing- 41. 2 2. 5 J 8 9. 7 41. 2 nButanol 39.6 1. 3 E-F 9 9. 7 .41. 2 Solvesso 100--- 39. 6 2. 25 I It is obvious 'fromtheabove data that the addition of a small amount of an aicohol toa hydrocarbon solution alcohol. I of an oxidized drying oil' polymer results in a greatly 2. 'Process accordingto claim 1 in which the alcohol reducediviscosity at a given non-volatile content or conis normal butanol. 1: Y versely 'an' increasednon-volatile content at a given 3.*Process" according to 'cl'aiml in which the alcohol viscosityp i 'fl is isopropanol. .T 1 E. T 1'. Example II.-Samples of the blown oils of Example I 4. Process according to claim 1 in which the alcohol containing various amounts of oxygen in hydrocarbon is diacetone alcohol. solution were further diluted with various alcohols in 5. A viscosity stable composition comprising a soluvarious amounts and allowed to age for up to 28 weeks tion of an oxidized butadiene polymeric drying oil in a in the form of simple varnishes and as enamels. Vishydrocarbon solvent having a kauri butanol value of at cosity determinations were made on each sample after least and 1 to 25 wt. percent of an alcohol selected 0, 1, 2, 4, 6, 8 and 12 week intervals. The following from the group consisting of isopropauol, normal butanol, results were obtained: and diacetone alcohol.

consisting-of isopr'opanol; normal buta'n'ol, and diacetone Varnish viscosities after aging EXAMPLE II. BLOWN O-OIL CONTAINING 7.94% OXYGEN Alcohol 1 Viscosity After Aging (Weeks) in Poise Sample NVM 2 Type Percent 0 1 2 4 6 8 28 10 N one 57. 5 10. 2 14.5 14. 5 14. 4 15. 3 15. 7 16. 7 25. 6 11 None 49. 1 3. 66 3. 93 4. 18 4. 52 4. 49 4. 4 6. 0 8. 1

l2 n-Butauol 14. 5 49. 2 2.0 2. O 2. 0 2.0 2. 13 2. 0 2. 1 2. 4

13- Isopr 11. 5 51. O 1. 89 1. 82 1. 82 1. 92 1. 1. 82 1. 82 2. 33

7 EXAMPLE III. BLOWN C-OIL CONTAINING 9.0% OXYGEN 14..- None.- 52.0 5.0 5. 0 5. 98 6. 3 6. 3 7. 5 9. 2 12. 9 15. None 46. 5 2. 38 2. 5 2. 58 2. 2. 91 3. 50 3. 7 5. 0 16 Diacetone Alcohol- 12. 3 46. 6 l. 72 1. 1. 89 2. 08 2. 08 2. 05 1. 89 2. 33 17 Isopropanol. 12. 5 46. 5 1. 29 1. 25 1.25 1. 31 1. 80 1. 32 1. 32 l. 48.

EXAMPLE IV. BLOWN O-OIL CON TAININ G 12.6 OXYGEN 18 None 47. 8 2. 38 2. 50 2. 88 3. 3 3. 2 3. 6. 03 19 Isopropyl Alcohol--. 12. 1 47. 4 0. 97 0. 92 1. 0 1. 13 l. 08 1. l6 1. 37 20- n-Bntrmnl 11. 9 47. 5 1. 13 l. 13 1. 3 1. 32 1. 32 1. 52 1. 89 21 Diacetone Alcohol- 12. 6 47. 1 1. 83 1. 65 1. 77 1. 89 2. 0 2. 25 2. 7 22 lsopr p 6. 8 50. 2 1. 53 1. 53 1. 65 1. 77 2. 0 2. 12 2. 5

1 Percent based on the total composition. I Percent polymer in the total. I Viscosity is in poise at the designated non-volatile content as determined by the Gardner Bubble viscometer White enamel viscosities after aging EXAMPLE V. WHITE ENAMEL BASED ON THE OIL OF EXAMPLE II Alcohol Krebs Units After Aging l I 1 Sample Pigment, Percent 1 NVM Type Per- 0 1 2 4 6 8 1.2

cent

l 23 Titanium Dioxide, 45%--- None 66.7 e5 99 102 105 24 Titanium Dioxide, 45%.-- Isopropyl Alcohol. 6.I 66.7 82 81 82 82 86 EXAMPLE VI. ENAMEL BASED ON C-OIL BLOWN T0 7.9% OXYGEN (PILOT PLANT) r l Pigment concentration is based on the total non-volatile, pigment plus polymer.

4 The alcohol concentration is based on the total composition including solvents.

1'21: Krebs Units rating are higher values=higher viscosities as determined by a paddle type Stormer Viscos e er.

Titanium Dioxide, 45%.-. N o

ne 93 100 100 Titanium Dioxide, 45%... Isopropyl Alcohol. 3.8

The above data clearly indicate that alcohols readily 6. Composition according to claim 5 in which the alstabilize clear oxidized polymer solutions and that this 5 cohol is isopropanol. effect is carried over to pigmented coating compositions. 7. Composition according to claim 5 in which the The nature of the present invention having been thus alcohol is normal butanol. fully set forth and specific examples of the same given, what is claimedas new and useful and desired to be secured by Letters Patent is: 70

8. Composition according to claim 5 in which the al- 1. The method for stabilizing the viscosity of solutions of oxidized butadiene polymeric drying oils in a hydrocarbon solvent having a kauri butanol value of at least 40 which comprises diluting the solution with 1 to tion of an oxidized oily copolymer of butadiene and styrene in a. hydrocarbon solvent having a kauri butanol value of at least 40 and 1 to 25 wt. percent of an alcohol selected from the group consisting of isopropanol, nor- 2S% by weight of an alcohol selected from the group 75 mal butanol, and diacetone alcohol.

2,908,585 7 10. A composition according "(0 claim 9- in which the ReEere'ncesCited in the-file of this patient alcohol 1s normal butanol. UNITED A S PATENTS '11. A co P08111011 according to claim 9 in whichlthe alcohol is isopropanol. 1,984,139 Koch Dec. 11,1934

1 2. A composition according to claim 9 inowhich. the 5 1,995,954 Albrecht fi May 26,1935

alcohol is diaccione alcohol. 2,712,561 Gleason c July}, 1955 

5. A VISCOSITY STABLE COMPOSITION COMPRISING A SOLUTION OF AN OXIDIZED BUTADIENE POLYMERIC DRYING OIL IN A HYDROCARBON SOLVEN HAVING A KAURI BUTANOL VALUE OF AT LEAST 40 AND 1 TO 25 WT. PERCENT OF AN ALCOHOL SELECTED FROM THE GROUP CONSISTING OF ISOPROPANOL, NORMAL BUTANOL. AND DIACETONE ALCOHOL. 